Method and apparatus for active voltage regulation in optical modules

ABSTRACT

A method and apparatus for active voltage regulation in optical modules utilize a voltage regulator to change the supply voltage provided to laser diode driver and receiver electronics to optimize module performance over temperature. The ambient temperature of the module is monitored. The outputs of the voltage regulator are controlled to provide voltages that are optimized with respect to temperature for the integrated circuits in the optical module. This control is implemented via a temperature sensitive feedback or a control input from a microcontroller with a temperature monitor input. The supply voltage is optimized to minimize the voltage required to achieve acceptable performance at a given temperature. Minimizing the supply voltage lengthens the lifetime of the integrated circuit and the optical module. The voltage regulator provides higher than standard supply voltages to a laser diode driver to compensate for higher laser voltage at low temperatures.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of, and claims priority and benefitsof, U.S. patent application Ser. No. 14/135,200 filed Dec. 19, 2013,which further claims the benefit of U.S. Provisional Application Ser.No. 61/747,302 entitled “Method and Apparatus for Active VoltageRegulation in Optical Modules” filed Dec. 29, 2012. The above-referencedapplications are hereby incorporated by reference in their entirety.

BACKGROUND OF THE INVENTION

This invention relates to a method and apparatus for voltage regulationin optical modules, particularly to optimize performance and extend theoperating temperature range.

Voltage regulators are often used in a variety of electronicsapplications. However, voltage regulators are not typically used inoptical modules, such as transceivers. When voltage regulators areutilized, they are used to provide power isolation, noise filtering,and/or to regulate a nominally fixed input voltage to a supply voltagerequired by the electronics in the optical module. Therefore, a needexists for active voltage regulation to adjust supply voltages forelectronics in an optical module to optimize performance overtemperature.

SUMMARY OF THE INVENTION

A method and apparatus for active voltage regulation in optical moduleshaving a voltage regulator to change the supply voltage provided tolaser diode driver and receiver electronics to optimize moduleperformance over temperature is provided. The ambient temperature of themodule may be monitored, and the outputs of the voltage regulator may becontrolled to provide voltages that may be optimized with respect totemperature for one or more of the integrated circuits in the opticalmodule. This control may be implemented via a temperature sensitivefeedback or via a control input from a microcontroller with atemperature monitor input. The supply voltage may be optimized tominimize the voltage required to achieve acceptable performance at agiven temperature. Minimizing the supply voltage to an integratedcircuit may also lengthen the lifetime of the integrated circuit, andtherefore the lifetime of the optical module. In addition, the voltageregulator may be used to provide higher than standard supply voltages toa laser diode driver to compensate for higher laser, particularlyvertical-cavity surface-emitting laser (VCSEL), voltage at lowtemperatures.

To this end, an embodiment of an optical module apparatus having activevoltage regulation to adjust supply voltages for electronics in anoptical module to optimize performance over temperature is provided. Theapparatus may have a combination of one or more semiconductor lightsources, one or more photodetectors, and zero or more opticalmodulators.

The apparatus may have one or more optical fibers and optics to couplelight from the semiconductor light sources into the optical fibers andfrom the optical fibers onto the photodetectors. The apparatus may alsohave driver and interface electronics, amplifiers, and microcontrollers.The apparatus may have a temperature monitor having an output and avoltage regulator with one or more outputs. Finally, the apparatus mayhave voltage regulator control electronics configured to adjust outputsof the voltage regulator with respect to the output of the temperaturemonitor.

In an embodiment, the semiconductor light source may be one or more ofthe following: a light emitting diode (LED), a vertical-cavitysurface-emitting laser (VCSEL), a Fabry-Perot laser and a distributedfeedback (DFB) laser.

In an embodiment, the photodetector may be one or more of the following:a p-l-n photodetector, an avalanche photodetector, ametal-semiconductor-metal (MSM) photodetector and a traveling wavephotodetector.

In an embodiment, the semiconductor light source may be directlymodulated or may be modulated using an optical modulator.

In an embodiment, the temperature monitor may be a thermistor or athermocouple.

In an embodiment, the optical fiber may be a single mode fiber or amultimode fiber.

In an embodiment, the optical module may be an optical transceiver, anoptical transmitter or an optical receiver.

In an embodiment, the optical module may transmit digital data and/oranalog data. In an embodiment, the optical module may be used toimplement data interconnects for control systems or for clock signaldistribution.

In an embodiment, the optical module may be an optical interrogator.

In an embodiment, the voltage regulator enables the optical module tooperate on different supply voltages.

In an embodiment, the voltage regulator may stabilize the voltage outputand may reduce supply voltage ripple.

In an embodiment, the output voltages of the voltage regulator may becontrolled to optimize performance of the optical module overtemperature.

In an embodiment, the output voltages of the voltage regulator may beadjusted to provide the minimum supply voltage required at a giventemperature by different electronics enabling power consumption to beminimized.

In an embodiment, the output voltages of the voltage regulator may beadjusted to provide the minimum supply voltage required at a given bitrate by different electronics enabling power consumption to beminimized.

In an embodiment, the output voltages of the voltage regulator may beadjusted to provide the minimum supply voltage required at a giventemperature by different electronics enabling the optical modulelifetime to be maximized. In an embodiment, the output voltages of thevoltage regulator may be adjusted to provide the minimum supply voltagerequired at a given bit rate by different electronics enabling theoptical module lifetime to be maximized.

In an embodiment, the output voltage of the voltage regulator used asthe supply voltage for the laser diode driver may be increased at lowtemperatures to compensate for higher VCSEL drive voltages at lowtemperatures.

In an embodiment, the output voltage of the voltage regulator used asthe supply voltage for the laser diode driver may be adjusted to ensuresufficient voltage headroom at given drive conditions.

In an embodiment, the output of the temperature monitor may be used as acontrol input by the voltage regulator control electronics.

In an embodiment, the voltage regulator control electronics adjust thevoltage output settings of the voltage regulator.

In an embodiment, the voltage regulator control electronics and thetemperature monitor may be the same components.

In an embodiment, the voltage regulator outputs may be controlled by thevoltage regulator control electronics to produce different voltages fordifferent electronics in the optical module.

In an embodiment, the temperature monitor may be integrated in theelectronics.

In another embodiment of the invention, a method of regulating voltagein an optical module is provided. The method may have the steps of:providing one or more semiconductor light sources, one or morephotodetectors, and zero or more optical modulators; coupling light fromthe semiconductor light source into an optical fiber and from theoptical fiber onto the photodetector; monitoring the temperature of theoptical module; providing a voltage regulator having an output; andadjusting the output of the voltage regulator with respect to thetemperature of the optical module.

In an embodiment, the method may have the step of providing the outputof the voltage regulator to the semiconductor light source as a drivevoltage.

In an embodiment, the method may have the step of providing the outputof the voltage regulator to the photodetector as a bias voltage.

In an embodiment, the method may have the step of controlling the outputof the voltage regulator outputs to produce different voltages fordifferent electronics in the optical module.

In an embodiment, the method may have the step of using the output ofthe temperature monitor as a control input for adjusting the voltageoutput settings of the voltage regulator.

In an embodiment, the method may have the step of adjusting the outputvoltages of the voltage regulator to provide a minimum supply voltagerequired at a given bit rate.

In an embodiment, the method may have the step of adjusting the outputvoltages of the voltage regulator to provide a minimum supply voltagerequired at a temperature

In an embodiment, the method may have the step of adjusting the outputvoltages of the voltage regulator to optimize performance of the opticalmodule over temperature.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of an embodiment of an optical module withactive voltage regulation wherein the control of the voltage regulatorover temperature may be implemented with a temperature dependentresistance.

FIG. 2 is a schematic diagram of an embodiment of an optical module withactive voltage regulation wherein the control of the voltage regulatorover temperature may be implemented using a microcontroller with atemperature monitor input.

DETAILED DESCRIPTION OF THE INVENTION

A method and apparatus for implementing active voltage regulation inoptical modules such as transceivers are provided. In the preferredimplementation, a voltage regulator may be used to provide a supplyvoltage that may be adjusted with temperature to integrated circuitswithin the optical module to optimize performance of the optical module.The voltage regulator circuit may provide more than one individuallycontrolled supply voltages if different integrated circuits in theoptical module require different voltages at a given temperature. Bycontrolling the supply voltages for integrated circuits in the opticalmodule such as laser diode drivers, transimpedance amplifiers, andmicrocontrollers, the performance of each of these components, as wellas other components such as VCSELs, may be optimized to reduce powerconsumption and improve module lifetime. In addition, the voltageregulator may provide a stable voltage supply at higher than nominalinput levels for the laser diode driver at low temperatures, enablingthe laser diode driver to drive VCSELs at low temperatures where theVCSEL voltage would be too high without this control. At highertemperatures, the supply voltage to the laser diode driver may bereduced to improve the lifetime of the laser diode driver. In addition,the voltage regulator may also be used to implement more commonfunctions such as voltage step-down and noise filtering. The voltageregulator may also be designed to accommodate a range of input voltages.

The control of the voltage regulator over temperature may be implementedin a variety of ways. Referring now to the Figures where like numeralsindicate like elements, a schematic diagram of an embodiment of anoptical module 10 with active voltage regulation is shown in FIG. 1. Thecontrol of the voltage regulator 20 over temperature may be implementedwith a temperature dependent resistance 90. FIG. 2 is a schematicdiagram of another embodiment of an optical module 10 with activevoltage regulation. The control of the voltage regulator 20 overtemperature may be implemented using a microcontroller 100 with atemperature monitor input 110.

For relatively simple monotonic temperature adjustment of the supplyvoltages, the preferred implementation may use a temperature dependentfeedback resistor 90 in the voltage regulator circuit as shown inFIG. 1. For designs that require more complex adjustment of the supplyvoltages versus temperature, the voltage regulator 20 may be controlledwith the microcontroller 100 that obtains the temperature of the opticalmodule 10 from the temperature monitor 110 such as a thermistor, asshown in FIG. 2.

FIG. 1 illustrates a schematic diagram of an embodiment of the opticalmodule 10 with active voltage regulation. The optical module 10 may beused to implement data interconnects for control systems and/or forclock signal distribution. The optical module 10 may be an opticalinterrogator.

The optical module 10 may have the voltage regulator 20. The control ofthe voltage regulator 20 over temperature may be implemented with thetemperature dependent resistance 90. The voltage regulator 20 may havean Input Voltage and outputs Supply Voltage 1 and Supply Voltage 2. Thevoltage regulator 20 may enable the optical module 10 to operate ondifferent supply voltages. For example, Supply Voltage 1 may be anoutput supply voltage provided by the voltage regulator 20. SupplyVoltage 1 may be connected as the supply voltage for a laser diodedriver 30. Further, Supply Voltage 1 may be adjusted to ensuresufficient voltage headroom at given drive conditions.

The optical module 10 may have an input for Input Data 35. The laserdiode driver 30 may take Input Data 35 and output Data 40 to avertical-cavity surface-emitting laser (VCSEL) 50. At low temperatures,Supply Voltage 1 may be increased to compensate for higher VCSEL drivevoltages at low temperatures. Supply Voltage 2 may be connected as asupply voltage for a transimpedance amplifier 60. The transimpedanceamplifier 60 may receive Data 65 from a photodetector 70. Thetransimpedance amplifier 60 may provide an output of Output Data 75 fromthe optical module 10. The optical module 10 may have one or moreoptical fibers 54 connected between the VCSEL 50 and the photodetector70 of the same or different optical modules. Optics 56 may also beprovided to facilitate coupling light 52 into and/or out of the one ormore optical fibers 54.

Control of the voltage regulator 20 over a range of operatingtemperatures may be implemented with control electronics 80 and/or thetemperature dependent resistance/resistor 90. The temperature dependentresistor 90 may be implemented by a thermistor, a thermocouple or thelike. Further, the voltage regulator 20 may stabilize the voltage outputand may reduce supply voltage ripple.

The output voltages of the voltage regulator 20 may be controlled tooptimize performance of the optical module 10 over a range of operatingtemperatures. The output voltages may also be controlled to minimizepower consumption of the optical module 10. Moreover, the outputvoltages may also be controlled to maximize the lifetime of the opticalmodule 10. For example, the output voltages of the voltage regulator 20may be adjusted to provide the minimum supply voltage required at agiven temperature by different electronics enabling power consumption tobe minimized. Also, the output voltages of the voltage regulator 20 maybe adjusted to provide the minimum supply voltage required at a givenbit rate by different electronics.

Also, the output voltages of the voltage regulator 20 may be adjusted toprovide the minimum supply voltage required at a given temperature bydifferent electronics enabling the lifetime of the optical module 10 tobe maximized. Similarly, the output voltages of the voltage regulatormay be adjusted to provide the minimum supply voltage required at agiven bit rate by different electronics enabling the lifetime of theoptical module 10 to be maximized.

The ambient temperature of the optical module 10 may be monitored, andthe outputs of the voltage regulator 20 may be controlled to providevoltages that may be optimized with respect to temperature for one ormore of the integrated circuits in the optical module 10. This controlmay be implemented via a temperature sensitive feedback 95 implementedwith the control electronics 80 and the temperature dependent resistor90 as shown in FIG. 1.

FIG. 2 illustrates a schematic diagram of another embodiment of anoptical module with active voltage regulation. Control of the voltageregulator 20 over a range of temperatures may be implemented with themicrocontroller 100 and the temperature monitor 110. Such an embodimentmay be preferred where more complex adjustment of the supply voltageswith respect to temperature may be required. The voltage regulator 20may be controlled with the microcontroller 100. The microcontroller 100may obtain the temperature of the optical module 10 from the temperaturemonitor 110. The temperature monitor 110 may be a thermistor. Thetemperature monitor 110 may provide an output 115 to the microcontroller100 that may provide the control input 120 to the voltage regulatorcontrol electronics 80. The output 115 of the temperature monitor 110may also provide the control input 120 to the voltage regulator controlelectronics 80. The voltage regulator control electronics 80 may adjustthe voltage output settings of the voltage regulator 20. In anembodiment of the invention, the voltage regulator control electronics80 and the temperature monitor 110 may be the same component. Further,the temperature monitor 110 may be integrated in the control electronics80. The voltage regulator outputs, for example, Supply Voltage 1 andSupply Voltage 2, may be controlled by the voltage regulator controlelectronics 80 to produce different voltages for different electronicsin the optical module 10. Although only two supply voltages are shown inthe drawings, additional supply voltages may be provided by the voltageregulator 20 in other embodiments of the invention.

The ambient temperature of the optical module 10 may be monitored, andthe outputs of the voltage regulator 20 may be controlled to providevoltages that may be optimized with respect to temperature for one ormore of the integrated circuits in the optical module 10. This controlmay be implemented via the temperature sensitive feedback as shown inFIG. 1 or via the control input 120 from the microcontroller 100. Thetemperature monitor 110 may provide the output 115 to themicrocontroller 100 that may provide the control input 120 to thevoltage regulator control electronics 80 as shown in FIG. 2.

It should be understood that various changes and/or modifications to thepresently preferred embodiments described herein will be apparent tothose skilled in the art. Such changes and/or modifications may be madewithout departing from the spirit and/or scope of the present inventionand without diminishing its attendant advantages. It is, therefore,intended that such changes and/or modifications be covered by theappended claims.

The invention claimed is:
 1. An optical module apparatus, comprising:one or more semiconductor light sources to emit light; a laser diodedriver coupled to the one or more semiconductor light sources to drivethe one or more semiconductor light sources; a temperature monitorconfigured to generate an output indicative of a temperature of theoptical module apparatus; a voltage regulator configured to generateoutput voltages and coupled to the laser diode driver to provide asupply voltage to the laser diode driver to drive the one or moresemiconductor light sources, wherein the supply voltage to the laserdiode driver is included in the output voltages; voltage regulatorcontrol electronics configured to adjust the output voltages of thevoltage regulator based at least in part on the output of thetemperature monitor; and a microcontroller including an input to receivethe output of the temperature monitor and configured to provide acontrol input to the voltage regulator control electronics based atleast in part on the received output of the temperature monitor.
 2. Theapparatus of claim 1 wherein the one or more semiconductor light sourcescomprise a light emitting diode (LED), a vertical-cavitysurface-emitting laser (VCSEL), a Fabry-Perot laser or a distributedfeedback (DFB) laser.
 3. The apparatus of claim 1 wherein thetemperature monitor comprises a thermistor or a thermocouple.
 4. Theapparatus of claim 1 wherein the voltage regulator is configured toenable the optical module apparatus to operate on different supplyvoltages.
 5. The apparatus of claim 1 wherein the voltage regulator isconfigured to stabilize the output voltages and reduce supply voltageripple.
 6. The apparatus of claim 1 wherein the voltage regulatorcontrol electronics is configured to control the output voltages of thevoltage regulator to adjust performance of the optical module overtemperature.
 7. The apparatus of claim 1 wherein the voltage regulatorcontrol electronics is configured to adjust the output voltages of thevoltage regulator to reduce supply voltage at a given temperature toreduce power consumption by the optical module apparatus.
 8. Theapparatus of claim 1 wherein the voltage regulator control electronicsis configured to adjust the output voltages of the voltage regulator toreduce supply voltage at a given bit rate of the optical moduleapparatus to reduce power consumption by the optical module apparatus.9. The apparatus of claim 1 wherein the temperature monitor isintegrated with voltage regulator control electronics, themicrocontroller or the laser diode driver.
 10. An optical moduleapparatus, comprising: one or more photodetectors to detect lightemitted from one or more semiconductor light sources; a transimpedanceamplifier coupled to the one or more photodetectors to receive data fromthe one or more photodetectors; a temperature monitor configured togenerate an output indicative of a temperature of the optical moduleapparatus; a voltage regulator configured to generate output voltagesand coupled to the transimpedance amplifier to provide a supply voltageto the transimpedance amplifier, wherein the supply voltage to thetransimpedance amplifier is included in the output voltages; voltageregulator control electronics configured to adjust the output voltagesof the voltage regulator based at least in part on the output of thetemperature monitor; and a microcontroller including an input to receivethe output of the temperature monitor and configured to provide acontrol input to the voltage regulator control electronics based atleast in part on the received output of the temperature monitor.
 11. Theapparatus of claim 10 wherein the one or more photodetectors comprise ap-i-n photodetector, an avalanche photodetector, ametal-semiconductor-metal (MSM) photodetector or a traveling wavephotodetector.
 12. The apparatus of claim 10 wherein the voltageregulator is configured to enable the optical module apparatus tooperate on different supply voltages.
 13. The apparatus of claim 10wherein the voltage regulator is configured to stabilize the outputvoltages and reduce supply voltage ripple.
 14. The apparatus of claim 10wherein the voltage regulator control electronics is configured tocontrol the output voltages of the voltage regulator to adjustperformance of the optical module over temperature.
 15. The apparatus ofclaim 10 wherein the voltage regulator control electronics is configuredto adjust the output voltages of the voltage regulator to reduce supplyvoltage at a given temperature to reduce power consumption by theoptical module apparatus.
 16. The apparatus of claim 10 wherein thevoltage regulator control electronics is configured to adjust the outputvoltages of the voltage regulator to reduce supply voltage at a givenbit rate of the optical module apparatus to reduce power consumption bythe optical module apparatus.
 17. The apparatus of claim 10 wherein thetemperature monitor is integrated with voltage regulator controlelectronics, the microcontroller, or the transimpedance amplifier. 18.The apparatus of claim 10 wherein the temperature monitor comprises athermistor or a thermocouple.
 19. A method of adjusting voltage in anoptical module, the method comprising: providing one or moresemiconductor light sources in the optical module, wherein a laser diodedriver is coupled to the one or more semiconductor light sources todrive the one or more semiconductor light sources; optically couplinglight from the one or more semiconductor light sources to an opticalfiber; monitoring, from a temperature monitor, a temperature of theoptical module based on an output generated by the temperature monitorindicative of the temperature of the optical module apparatus;providing, from a voltage regulator, an output including one or moresupply voltages to the laser diode driver to drive the one or moresemiconductor light sources; using voltage regulator control electronicsto adjust the output of the voltage regulator based at least in part onthe monitoring of the temperature of the optical module; and providing,from a microcontroller that received the output of the temperaturemonitor, a control input to the voltage regulator based at least in parton the output of the temperature monitor received from the temperaturemonitor.
 20. The method of claim 19 further comprising: using monitoringof the temperature in a feedback circuit for adjusting the output of thevoltage regulator.
 21. The method of claim 19 further comprising:adjusting the output of the voltage regulator to adjust supply voltageto the laser diode driver at a given temperature provided based on theoutput of the voltage regulator.
 22. The method of claim 19 furthercomprising: adjusting the output of the voltage regulator to adjustperformance of the optical module over a range of temperature.
 23. Themethod of claim 21 further comprising: adjusting the output of thevoltage regulator to adjust supply voltage to the laser diode driver ata given bit rate provided based on the output of the voltage regulator.24. A method of adjusting voltage in an optical module, the methodcomprising: providing one or more photodetectors in the optical moduleto detect light emitted from one or more semiconductor light sources;optically coupling light from an optical fiber to the one or morephotodetectors; monitoring, from a temperature monitor, a temperature ofthe optical module based on an output generated by the temperaturemonitor indicative of the temperature of the optical module; providing,from a voltage regulator, an output including one or more supplyvoltages to a transimpedance amplifier to provide a supply voltage tothe transimpedance amplifier; using voltage regulator controlelectronics to adjust the output of the voltage regulator based at leastin part on the monitoring of the temperature of the optical module; andproviding, from a microcontroller that received the output of thetemperature monitor, a control input to the voltage regulator based atleast in part on the output of the temperature monitor received from thetemperature monitor.
 25. The method of claim 24 further comprising:using monitoring of the temperature in a feedback circuit for adjustingthe output of the voltage regulator.
 26. The method of claim 24 furthercomprising: adjusting the output of the voltage regulator to adjustsupply voltage to the transimpedance amplifier at a given temperatureprovided based on the output of the voltage regulator.
 27. The method ofclaim 24 further comprising: adjusting the output of the voltageregulator to adjust performance of the optical module over a range oftemperature.
 28. The method of claim 24 further comprising: adjustingthe output of the voltage regulator to adjust supply voltage to thetransimpedance amplifier at a given bit rate provided based on theoutput of the voltage regulator.